Can anyone tell me where to get a narrow top mount turbo manifold with T25 flange for my SR20DET project?

You can try this place. They are pretty flexible and helpful with their products and fairly reasonable.

http://www.jgstools.com/turbo/

I think you'll find that most top mount turbo manifolds for the SR20 will have the T3/T4 flange instead of the T25/28 flange. This is good and bad obviously....you've already got the T25/28 turbo ON the SR20, and there's plenty of upgrades for those, but they're usually pretty pricey, on the other hand, T3/T4's are great turbos and spool real fast by design and are a lot cheaper and easier to get thanks to the booming (and lame) fast and furious crowd. They're also rebuildable fairly cheap whereas the T25/28's aren't truly rebuildable without basically paying the same price a new one would cost.

All this has got me in a weird position. I've got the exact turbo I'd like to use on the SR20DET going into my 1200...it's the roller bearing S15 turbo, perfect for street/track use and about 300rwhp. Unfortunately, the turbo manifold is T3/T4, so I gotta get one of those turbos instead. I'm still going to use the S15 turbine on my 180SX, but I wish I had a top mount T25 manifold so I could just use the perfectly matched (for what I want to do) S15 turbine. So there you go. Good luck with your project. I'm going to dive into mine really soon, I'm just waiting for a parking spot to open up at the auto shop....any day now!

-ANdy

I found this AU company
www.beyondthelimit.com.au

But I don't know if its T25? It's told to be custom. Maybe they can do it with T25.
I'll try to find out.